1. Field of the Invention
The present invention relates to a thermally activating apparatus of a thermosensible adhering sheet formed with a thermosensible adhesive layer showing a nonadhering property in normal time and manifesting an adhering property by being heated on one face of a sheet-like base member and used as, for example, an adhering label, particularly to a technology of cleaning a head or the like of a thermally activating apparatus constituting heating means by a thermal head.
2. Description of the Related Art
In recent years, a pasting label used as a POS label of a food product, a physical distribution/delivery label, a label for medical treatment, a baggage tag or a display label of bottles/cans, is frequently of a type having a pressure sensitive adhesive layer on a rear side of a printable face (record face) and storing in a state of pasting an exfoliating sheet (separator) thereon to tackedly adhere thereto. However, the pasting label of this type needs to exfoliate the exfoliating sheet from the pressure sensitive adhesive layer when used as the label and therefore, there is a drawback of necessarily bringing about waste.
Hence, as a system for dispensing with the exfoliating sheet, there have been developed a thermosensible adhering label provided with a thermosensible adhesive layer showing a nonadhering property in normal time and manifesting an adhering property by being heated on a rear face side (a side opposed to a printable face) of a label-like base member and a thermally activating apparatus for manifesting the adhering property by heating the thermosensible adhesive layer of the label. For example, JP-A-11-79152 discloses a technology for heating the thermosensible adhesive layer by bringing a head having a single or a plurality of resistance members (heat generating elements) provided above a ceramic board as a heat source as in a thermal head utilized as a printing head of a thermal printer apparatus.
FIG. 7 is an explanatory view showing a constitution of a conventional thermally activating apparatus. The thermally activating apparatus is constituted by a thermally activating platen roller 52 as carrying means for carrying a thermosensible adhering label 60 and a thermally activating thermal head 51 having a heat generating element 514 as heating means. Further, the thermally activating platen roller 52 functions also as a pressing member for pinching the thermosensible adhering label 60 between the thermally activating platen roller 52 and the thermally activating thermal head 51.
In FIG. 7, notation 510 designates a ceramic board as a heat radiating board on which a glaze layer 511 as a heat storing layer is formed over an entire face thereof by printing, for example, a glass paste and sintering the glass paste at predetermined temperatures (for example, about 1300 through 1500° C.). Further, a heat generating element (resistance member) 514 is formed and an electrode 512 for conducting electricity to the heat generating element 514 is formed in a predetermined pattern above the glaze layer 511. Further, an IC unit 515 for controlling to conduct electricity to the heat generating element 514 is formed above the glaze layer 511 and an upper side thereof is protected by a sealing portion 516 comprising a resin or the like. Further, a protective layer 513 comprising hard ceramics or the like is formed thereabove to prevent oxidation or wear of the electrode 512 and the heat generating element 514.
According to the above-described thermally activating apparatus, electricity is conducted to the heat generating element 514 in a state in which the thermosensible adhering label 60 is brought into contact with the protective layer 513, thermal energy provided thereby is applied to the thermosensible adhering label 60 via the protective layer 513 and therefore, thermal activation of the thermosensible adhesive layer is firmly carried out. Further, heat from the heat generating element 514 can efficiently be conducted to the thermosensible adhesive layer and therefore, an advantage of reducing power consumption is achieved.
However, according to the above-described thermally activating apparatus, the thermosensible adhesive layer is exposed from one face of the thermosensible adhering label 60 and therefore, there is observed a phenomenon in which remaining substances G1 and G3 comprising a portion of the thermosensible adhesive layer softened by being heated or a denatured product thereof are adhered to the thermally activating thermal head 51. Particularly, when heating means is constituted by the thermal head, it seems that the remaining substances are liable to adhere to the thermally activating thermal head 51 since the thermally activating thermal head 51 and the thermosensible adhesive layer are brought into contact with each other to directly heat.
Further, when the remaining substances G1 and G3 are gradually accumulated, an efficiency of conducting heat from the heat generating element 514 to the thermosensible adhesive layer is lowered and therefore, there poses a problem that the thermosensible adhesive does not manifest a sufficient adhering property in the same heating time period. In this case, although the thermal activation can be carried out sufficiently by prolonging the heating time period, when the time period is prolonged, power consumption is increased and a time control is needed and therefore, the control becomes complicated.
Further, a printing processing and a thermally activating processing are continuously carried out in a state of adhering the remaining substances G1 and G3 to the thermally activating thermal head 51 and therefore, the remaining substances G1 and G3 may be retranscribed to the thermosensible adhesive layer of the thermosensible adhering label 60 to deteriorate adhering force. Further, the remaining substances adhered to the thermally activating thermal head 51 are heated by a number of times and therefore, there is also brought about a drawback that the remaining substances are carbonized after elapse of a long period of time and cannot be removed easily.
Further, there is also a case in which the remaining substances G1 and G3 adhere to the peripheral face of the thermally activating platen roller 52 and in this case, there is a concern that a remaining substance G2 adheres to a side of a surface (printable face) of the thermosensible adhering label to contaminate a printing face. Further, when the remaining substance G3 on a side of inserting the thermosensible adhering label 60 is enlarged by continuous thermally activating processing (for example, thermally activating processing of a sheet length of 500 m), performance of inserting labels is deteriorated and there is a concern of bringing about sheet jamming.
Therefore, it is necessary to periodically clean the remaining substances of the thermosensible adhesive or the like adhered to the thermally activating thermal head 51, however, for cleaning the remaining substances, the thermally activating thermal head 51 needs to detach from the thermally activating apparatus 50 and therefore, considerable labor and time is needed. Further, in cleaning the remaining substances, it is necessary to interrupt the printing operation for a comparatively long period of time and shut off electricity conduction to the heat generating element 514 and therefore, continuous operation of a printer apparatus becomes difficult and an operational rate of the apparatus is lowered.